The present invention relates to an improvement to brake regulators for motor vehicles and more particularly to regulators of the type comprising a housing equipped with a bore, a simple or differential piston sliding in the bore and delimiting there a first and a second pressure chamber capable of being connected to a source of fluid under pressure and to one of the brake circuits of the vehicle respectively, the chambers communicating with one another by means of a passage made in the piston, a valve mounted in the passage and stressed elastically to bear sealingly against a seat formed on the piston, and a return spring interposed between a movable element, the position of which varies as a function of the load of the vehicle, and the piston, so as to stress the latter towards the bottom of the second chamber, in a rest position in which the valve is set apart from its seat by a stop.
Such a brake regulator, more especially designed as a "compensator", is particularly described, and its function and operating mode explained, in FR-A-2,383,048 or EP-A-0,156,666 (Perrin U.S. Pat. No. 4,615,566).
In a regulator of the above-mentioned type, it is desirable, to obtain a correct operation of the brakes when the actuating fluid is put under pressure, to have a relatively wide opening of the valve, that is to say a sufficient setting of this valve (usually consisting of a ball) apart from its seat in the rest position of the piston. Moreover, it is necessary as far as possible to reduce the stroke of the piston between its rest position and its position corresponding to the activation point of the compensator, that is to say that in which the ball comes to rest on its seat, the purpose of this being to avoid disturbing the information transmitted to this piston in the form of a force reflecting the load of the vehicle.
Since these two requirements are incompatible in principle, an object of the present invention is to correct this deficiency, and to achieve this it provides a brake regulator of the above-mentioned type, in which the relative movement of the ball and piston is amplified in relation to that of the piston and body.